Carburetor



Oct. 25, 1932. w. STURM 1,884,359

CARBURETOR Filed June 18. 1929 'by to make the mixture uniform,

Patented Oct. 25, 1932 WILHELM STURM, OF

STUTTGART, GERMANY, ASSIGNOR TO ROBERT BOSCH AKTIEN- GESELLSCHAFT, OF STUTTGART, GERMANY CARBURETOR Application filed June 18, 1929, Serial No'. 371,832, and in Germany July 9, 1928.

The present invention relates to carburetors and more particularly to the injection type and having an air throttle and float chamber regulated as in the construction described in the specification of my copending application Serial No. 265,778 which matured into Patent 1,840,279, granted Jan. 5, 1932. In car buretors of this type an auxiliary throttle opens an auxiliary air duct parallel to the main air jet or choke tube immediately the quantity of air required by the engine is greater than that capable of flowing through the main air jet in the short time available.

This condition arises more particularly with fast running under load. The air entering through the auxiliary air duct does not however carry along any fuel with it. It meets the current of mixture coming from the main air jet and mixes with it in the suction pipe thereby diluting the mixture. If therefore no special measures are taken the mixture will be poorer the more auxiliary air is drawn in, since the quantity of the one component of the mixture, namely the fuel, remains constant.

In order to adapt this quantity to the increasing admission of auxiliary air and therethe throttle regulating the auxiliary air current is allowed, according to the present invention, to act on elements whichincrease the flow of fuel out of the jet when the throttle opens and vice versa.

Five forms of construction ofcarburetors according to the present invention are shown diagrammatically in longitudinal section in the drawing. Each of the five figures shows one example.

So far as there is coincidence the separate elements have the same reference letters in all the forms of construction.

In the first form of construction shown in Figure 1 the carburetor housing is illustrated at a, the main throttle at b, the float chamber at e, conduits from said float chamber at 70, m and h respectively, the conduit m branching off from the conduit la and having a throat t whilst the conduit 70 at a position between the branch m and the float chamber 6 is provided with a throat 11.

The main air choke tube or air jet 0 is arranged atone side of the mixing pipe or chamber a and is of narrow cross section to leave a conduit 1 between itself and the remote wall of the carburetor mixing chamber a. An auxiliary choke tube or air jet (1 is mounted so that its upper end extends into the lower end of the main choke tube 0.

The valve 2 regulating the auxiliary air current is constructed as an automatic valve with two unequal vanes. It positions itself according to the vacuum obtaining to the rear of it in the direction of flow.

This vacuum commences to increase as soon as the charge required by the engine can no longer be sucked through the main air jet 0 Without any throttling action, assuming of course that the main throttle b is sufficiently open. I i

As soon as the valve 2 commences to open and as soon therefore as the air'current sucked through the auxiliary duct l is greater a small gear wheel amounted onthe pivotal axis of the valve moves a valve cone 5 which is mounted in the housing a on the cylinder shaft and is provided with suitable meshing teeth.

The valve cone approaches the mouth n of the vapour duct m and throttles the supply of air to this duct so that with increasing flow of air through the auxiliary duct Z the quantity of vapour passing into the supply tube 7: decreases and accordingly the quantity of fuel emerging from the supply tube increases.

The second example shown in Figure 2 differs from the first only in a slightly modified actuation of the valve cone 5 varying the cross section of passage of the vapour duct. A bifurcat-e extension 6 of the valve 2 displaces the valve cone 5 positioned in the housing a when the valve itself moves. In this case also the section of the vapour duct decreases with increased o ening of the valve, and accordingly also the cam-air supply, so that correspondingly-more fuel is sucked from the supply pipe is. Y

In the third form of construction shown in Figure 3 a memb r 7 similar to a slide valve is provided instead of the valve cone used in the first two examples which is arranged diwithin said main choke tube,

v air passage external to said 111 rectly on the valve 2 and which covers the mouth n of the vapour duct to a greater extent with increased opening of the automatic valve 2.

In the fourth example shown in Figure 4 no vapour duct is provided. The cross-section of the 'outletof the supply duct (spray jet) is here altered in accordance with the positlon of the valve 2. For this purpose a regulating needle 8 passing centrally through the air jet is provided which is articulated at 10 to alever 9 articulatedto thehousing. The valve 2 when it opens strikes against the lever'9 lifts it and accordingly the needle 8 also, whereby the cross-section of the outlet of the supply pipe is and accordingly the quantity emerging are increased according to the progressive opening of the valve 2. I

The fifth example as in Figure 5 shows the manner in whichthe quantity of fuel emerging from the supply pipe can be altered byvarying the suction force feeding it. In this case an extension 11 on the valve 2 forces a cover plate 12 01f the auxiliary air jet (Z to an increasing extentwhen the valve opens The suction efl'ect in'the neck of the auxiliary jet d could however be ada ted to the requirements by allowing one or oth'of the jets c and'd, constructed one in the other, to

be dis laced longitudinally in one another in accor ance with the movement of the valve.

What I claim is:

2 -l. A carburetor comprising, in combination, a float chamber, a nnxmg pipe, a main choke tube located in said mixlng ipe and connected to said float chamber, said mixing pipe havingan air passage external to the main choke tube, an auxiliary choke tube an atomizing jet connected to the fuel space of said float cham ber, an auxiliary air throttle controlling the 'n choke tube, and a pipe connected to the atomizing jet supply pipe, the opening to which is controlled directly from said air throttle.

2. A carburetor comprising, in combination, a float chamber, a mixing pipe, a main choke tube located in said mixing pipe and connected to said float chamber, said mixing pipe having an air passage external to the main choke tube, an auxiliary choke tube within said main choke tube, an atomizin jet connected to the fuel space of said oat chamber, an auxiliary air throttle controlling the air passage external to said main choke tube, a pipe connected with said fuel supply to the atomizing jet, a valve controlling said pipe and means interconnecting said valve with said auxiliary air throttle.

3. A carburetor comprising in combination a float chamber-, a mixing pipe, a main choke tube located in said mixing pipe and connected to the air space of said float chamber, said mixing pipe formin a passage external to and in addition to t e main choke tube, an auxiliary choke tube within said main choke tube, an atomizing jet within said auxiliary choke tube and connected to the fuelspace of said float chamber, a main air throttle controllingthe air passage of the mixing pipe before the choke tubes and said passage external to the choke tubes, an auxiliary air throttle only controlling said air passage .external to the choke tubes and means interconnected therewith to control the flow of fuel from the supply jet.

4. A carburetor comprising in combination, a float chamber, a mixing pipe, a main choke tube located in said mixlng pipe and connected to the air space of said float chamber, said mixing pipe forming a passage external to andin addition to the main choke tube, an auxiliary choke tube within said main choke tube, an atomizing jet within said auxiliary choke tube and connected to the 

